For years, food companies have been catering to the healthy eating crowd promising that their stuff has ‘all natural’ ingredients.

But what exactly does 'all natural' mean?

A recent string of customer lawsuits are charging that there is no clear definition, giving companies free reign to define it however they want.

A recent string of lawsuits against brands like Wesson cooking oil and Skinnygirl Margaritacharging that there is no clear definition, giving companies free reign to define it however they want

Food policy expert Michele Simon told the Wall Street Journal: 'The word hasn’t been defined well enough at all, so for years companies have been able to get away with basically defining it themselves.'

Kashi cereal, Wesson cooking oil, Arizona Iced Tea and Skinnygirl Margarita have all been challenged in court over their 'natural' ingredients.

While several lawsuits have been filed against those manufacturers, lawyers and legal eagles are quick to blame the Food and Drug Administration for failing to act.

Attorney Stephen Gardner of the Center for Science in the Public Interest, told the WSJ: 'We badly want [the FDA] to provide some clarity on the issue.'

The most clear definition provided by the agency, written more than 20 years ago, says 'natural' means ‘Nothing artificial or synthetic... is included in, or has been added to, the product that would not normally be expected to be there.'

Natural? Kashi cereal is one of many products that boasts 'natural' ingredients, but some argue that the cereal's manufacturers are defining it how they want

While the FDA admits they may have dropped the ball on providing an explanation, it's not one of their top priorities.

FDA spokeswoman Siobhan Delancey said: ‘With the precious dollars the FDA has, we largely choose to focus on topics that affect public safety.

'The "natural" issue doesn’t. That's not to say it's not important, but we frankly have more pressing things to deal with.'

ConAgra Foods, the makers of Wesson cooking oil, said they would not comment on pending litigation, but said 'we stand behind the accuracy of our labelling.'

A similar suit filed against Skinnygirl Margarita, which alleges the cocktail can't be considered 'all natural' because it contains the preservative sodium benzoate, has been dismissed as 'frivolous' by the drinkmaker.

Eager to avoid the financial and public exposure, most of the sued companies are settling the ‘natural’ lawsuits out of court.

The dollar amounts of the settlements tend to remain sealed, some leaked settlements have totalled in the 7-figure range, according to the WSJ.

To your health: Arizona is one of several brands that are having their ingredients challenged in lawsuits over the '100 per cent natural' claim